The fusion of metallic nickel with sodium dioxide was reported in 1896 by W. L. Dudley in 18 J. Am. Chem. Soc. 901. Dudley fused sodium dioxide in a nickel crucible with nickel metal at a cherry-red heat, about 700.degree. C. to 800.degree. C., for about one hour. After cooling, the contents were submerged in water. The brown crystals formed were washed to remove alkali. The crystals were then dried at 110.degree. C. The crystals were analyzed and believed to be the dihydrate Ni.sub.3 O.sub.4.sup.. 2H.sub.2 O, with 0.7 wt.% cobalt as an impurity. A cobalto-cobaltic dihydrate Co.sub.3 O.sub.4.sup.. 2H.sub.2 O was also described as obtained by exposing to moist air Co.sub.3 O.sub.4, prepared by heating cobalt carbonate. These materials were believed to be new compounds but no active battery material or electrochemical use was suggested.
Jackovitz and Pantier, in U.S. Pat. No. 3,941,614, discovered a process which would provide an improved activated battery material, by chemically reacting NiO with effective amounts of Na.sub.2 O.sub.2, generally at melt fusion temperatures of about 950.degree. C. to 1,025.degree. C., to form NaNiO.sub.2, which was then hydrolyzed to form Ni(OH).sub.2. Due to the high temperatures involved, the fusion reaction was conducted in a nickel reaction vessel.
Preparing Ni(OH).sub.2 by starting with nickel metal, would require a prolonged oxidation step, sure to degrade the reaction vessel. The Jackovitz and Pantier process, while eliminating the prolonged oxidation step by starting with NiO, still required relatively large amounts of Na.sub.2 O.sub.2 and still caused some corrosion of the very expensive nickel reaction vessel required in the melt-fusion step.
There is a need then for an improved method of making Ni(OH).sub.2 active battery material from inexpensive NiO, at lower temperatures and requiring less Na.sub.2 O.sub.2, so that less expensive alumina, porcelain, etc. reaction vessels can be used repeatedly, with resultant savings in a commercial operation.